The present invention relates to constant fluid flow regulators and more particularly to a flow regulator having a spring biased piston and being capable of maintaining a constant fluid flow rate in both high pressure, low volume and low pressure, high volume environments with changes in inlet or outlet pressure. The present invention also accommodates high pressure, high volume and low pressure, low volume systems. Prior art constant fluid flow regulators vary fluid flow through the piston by movement of the piston that varies the flow pressure through this piston or by change in the spring tension. In contrast, the present invention varies fluid flow by varying the flow passage through or around the piston. More specifically, constant fluid flow regulators taught in prior art regulate fluid flow by adjustment screws that directly vary spring tension by attachment to the piston spring itself. Other regulators change fluid flow by altering piston position via springs and ball bearings located over the piston. The system employing springs and ball bearings is subject to extreme torque due to the fluid pressure in the chamber.
Also, prior art constant fluid flow regulators capable of accommodating low pressure, high volume fluid flow often employ sliding sleeves for opening and closing parts of the regulators. Additionally, multiple poppet type valves may be used for low pressure, high volume fluid flow regulation. The above prior art, however generally cannot accommodate high pressure, low volume fluid flow. This invention, on the other hand, is able to provide constant fluid flow in high or low pressure and high or low volume ranges. The present invention is also different from the above sliding sleeve and multiple poppet type valves in that the piston of the valves of the prior art move relative to the valve body to vary fluid flow as the pressure changes, while the piston of the present invention does not move substantially relative to the valve body after fluid flow has stabilized. Instead, constant spring force on the piston in the present invention allows constant flow with changing pressure. The present invention thus experiences less wear and tear from moving parts.
Additionally, U.S. Pat. No. 4,893,649 issued to Skoglund and U.S. Pat. No. 3,958,596 issued to Gerrard both disclose valves in which fluid flow variation is implemented by an adjustable valve seat. Adjustment of the valve seat adjusts the spring tension, which in turn alters the pressure differential across the piston. However, both of the above prior art patents employ threaded, screw-type mechanisms for adjusting the valve seat which are difficult to operate, have a narrow operating range, and are prone to breakage in high pressure environments.
Also, the screw-type valve seat adjustment mechanisms of the above prior art references both impede fluid flow through the valve. U.S. Pat. No. 4,893,649, discloses a valve in which the fluid outlet is oriented perpendicular to the fluid inlet in order to accommodate the valve seat adjustment mechanism. This angled fluid flow pathway results in a more complex valve design as well as increased fluid turbulence and higher pressure drops. U.S. Pat. No. 3,958,596 issued to Gerrard teaches a valve in which the fluid outlet passes axially through the valve seat adjustment screw. This valve seat adjustment mechanism configuration is difficult to use while the valve is in operation. The valve of the present invention, on the other hand, adjust fluid flow by varying fluid flow through or around the piston.